Jacketed Kettle

**Double-Layer Kettle for Jam Production**

The double-layer kettle is a versatile piece of equipment used in various industries, including food production. It is particularly effective for making jam, offering functionalities such as blanching, boiling, heating, sterilizing, and more. Below is a detailed process for jam production using a double-layer kettle:

### **1. Raw Material Processing:**

- **Selection:** Use high-quality fruits like apples, strawberries, or kiwis with high ripeness and citric acid content.

- **Preparation:** Core, peel, and slice the fruits. Soak them in citric acid or salt water to preserve color. For harder-to-clean fruits like strawberries, trim and rinse thoroughly.

### **2. Softening and Beating:**

- **Softening:** Heat the fruit in a steam-coated kettle with an equal volume of water until softened (typically no more than 10 minutes).

- **Beating:** Transfer the softened fruit to a barrel, add a color preservative (0.03–0.04%), and blend into a smooth paste. Sieve twice for uniformity, ensuring the pulp is free of particles and impurities.

### **3. Adding Sugar and Concentrating:**

- **Concentration:** Use a steam-stirred kettle to concentrate the pulp. Maintain steam pressure at 1.0–1.5 kg/cm² while stirring to prevent charring.

- **Final Steps:**

- Add "jam stabilizer" dissolved in water.

- Adjust acidity and flavor with preservatives and additional acid.

- Stir thoroughly until smooth.

### **4. Filling and Sterilization:**

- **Filling:** Immediately fill cans with the hot jam, ensuring the temperature does not drop below 85°C.

- **Sterilization:** Seal the cans and sterilize in boiling water or steam at 100°C for 20 minutes.

- **Cooling and Finishing:** Cool the cans in stages and wipe them dry.

### **Quality Criteria:**

- **Spreadability:** The jam should not flow quickly when scraped and should spread evenly on bread.

- **Texture:** Achieve a soft, uniform texture by adding the appropriate amount of "jam stabilizer."

### **Market Trends:**

- **Unfrozen Jam:** Increasingly popular for use in popsicles and ice cream due to its soft texture and simple production process.

By following these steps, the double-layer kettle ensures efficient and high-quality jam production, meeting both traditional and modern market demands.